Achievements
Complete each of the following achievements below to get the allotted gamerscore:

All Rewards Unlocked (30) - Unlock all rewards.
Ability First Kill (5) - Perform a kill using your ability for the first time in challenge mode.
Ability Master (10) - Perform 10 frags in a row with only your abilities in challenge mode.
ArenaMaster (20) - Perform 5 kills without being killed in a ranked match.
BlackOp Campaign Completed (20) - Complete all challenges in the BlackOp Campaign.
Bishop Campaign Completed (20) - Complete all challenges in the Bishop Campaign.
Guardian Campaign Completed (20) - Complete all challenges in the Guardian Campaign.
Marathon (35) - Score 1,000,000 points.
Challenges Master (10) - Win Death Match without being killed in a challenge.
First Blood (5) - Try to be the first one that kills an enemy in challenge mode.
Slayer (20) - Get 100 kills in Xbox LIVE ranked match.
Tutorials Completed (5) - Complete the tutorial for each character.